Insulated conducting member and method of applying the insulation



G. CAMILLI June 6, 1944.

INSULATED CONDUCTING MEMBER AND METHOD OF APPLYING THE INSULATION Filed June 25, 1942 2 Sheets-Sheet 1 Wm 00 n moj E wk M w wb I s w H g ID June 6, 1944. CAWLLI 2,350,724

INSULATED CONDUCTING MEMBER AND METHOD OF APPLYING THE INSULATION Filed June 23, 1942 2 Sheets-Sheet 2 Inventor: Guglielmo Camilli,

b His Attorneg.

Patented June INSULATED CONDUCTING Marissa AND METHOD OF APPLYING THE INSULATION Guglielmo Camilli, Plttsileld, Mass., aasignor to General Electric Company, a corporation of l ew York Application June 23, 1942, Berhl No. 8,118

' 9 Claims.

My invention relates toelectrical insulation and to an improvedmethod of applying an insulating material to an electrically conducting article, and to the article which is so insulated.

Heretoiore, it has been common practice when applying a high voltage insulation to electrically conducting articles, such as some coils, to apply a suitable tape, such as crepe paper, by taping the coil by hand. An improved method of hydraulically applying an insulating covering in a relatively short time is described and claimed in a copending application 8. N. 326,042 to Camilli, Hemphill and Endicott, tiled March 26, 1940, which issued on July 21, 1942, as Patent 2,290,671, and which is assigned to the same assignee as this present invention.

It is an object oi my invention to provide an improved method of the type described in the above-mentioned patent for insulating an electrically conducting member.

Another object of my invention is to provide an improved insulating covering for'an electrically conducting article.

A further object of my invention is to provide a coil winding member for an electric induction apparatus with an improved insulating cover-hi8.

Further objects and advantages of my invention will become apparent irom the following description referring to the accompanying drawings, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part oi this specification.

In the drawings, Fig. l diagrammatically illustrates an apparatus ior carrying out my 1m proved-method; Hg. 2 is an end view of a portion of the apparatus illustrated in Fig. 1; Fig. 3 is a sectional side elevation of a winding which is covered with my improved insulation; Fig. 4 is a sectional side elevation of a coil winding which may be covered with my improved insulating covering; 1'18. 5 is an end view oi the coil winding of Pig. 4, and Pig. 6 illustrates an apparatus for carrying out a modification of my improved method.

The improved method, described in the abovementimed patent, of insulating an electrically conducting article, such as a coil winding, includes-the steps of placing a permeable screen around the article to be coated and spacing the screen from the article to provide a fluid channel. The article isthen placed in a bath including a fluid having finely divided particles or bits of insulating material suspended therein. A difference-oi pressure is produced between the fiuid inside and outside the screening so that the fluid may pass through the screen and deposit its suspension. The thickness of a covering which may be so. deposited may, of course, be dependent on such factors as the relative values of pressure between' that inside and outside of the screen, the size of the insulating particles suspended in the fluid, and the type of fluid, Furthermore, as the insulating covering builds up, the fluid which deposits its suspension must pass through the already. deposited insulation, so that a pressure drop will obtain through the covering which has already been applied. Assuming constant conditions, therefore, a thickness will be reached when no further fluid will pass through the already deposited insulating covering, so that no further insulation will be deposited.

Referring to the drawings, in Fig. 1 I have illustrated-an. apparatus for carrying out my invention. However, it is to be understood that any other suitable apparatus may be employed. The apparatus includes a pair of separable mold portions II and II which maybe attached together by a plurality of screwsv and bolts It. The mold portions may have a cavity of any suitable shape for accommodating the particular article which is tobe insulated, and in the arrangements illustrated in Figs. 1 and 2 it will be seen that the molds when placed together have a toroidal shaped cavity for receiving a coil winding it for an electric induction apparatus. The coil to be covered by my improved method includes any suitable number of turns It and a permeable envelope II which is spaced from the outer surface of the turns by suitable spacers It to provide a channel arrangement H. A pipe is may be passed over the ends of the turns which pipe connects to the channel inside the screen, such as through an opening I! in the screen. The coil winding may be properly disposed in the mold cavity by smpendlng it through the pipe l8. The inner surface of the mold portions Ill and H is provided with permeable portions or screens 20 and II which are spaced from the screen l5 by a distance equal to the thickness of the insulation which is desired. The space between the two screens may be sealed off by a cover member 22 and this space may be in turn connected by a pipe 23 to a tank 24.

In order to hydraulically apply the insulation around an electrically conducting article such as asbestos, suspended therein. This fluid with its insulating suspension may then be forced into the space between the two screens by suitable pressure, such as water pressure, through a pipe 25 which has a valve 28. In order to remove the fluid which passes through the screen ii the pipe It may be connected to any suitable vacuum pump. In order also to remove the water which passes out through the perforated or second screen portions 20 and 2| in the mold, a pipe 21 may connect from the space between the screen portions and the outside 01' the mold tank and the pipe It which leads to the vacuum pump. with a suitable pressure diflerential between the space outside the screen I! and inside the'screens 2| and 2| so that this fluid pressure will be higher than that present inside the screen I! and between the mold screens 20, 2| and the outside surface of the mold, the fluid in the mold cavity will pass both through the screen It depositing its suspension. and through the screens 20 and 2| also depositing its suspension. A fluid with a suitable proportion of insulating bits may continue to be introduced into the mold cavity through the pipe 23 until the space between the screen l1 and the mold screens 20 and 2| is substantially filled with insulation. when this is done a valve 20 in the pipe 23 may be closed and a pump cgnnected to a pipe II to withdraw the surplus fluid in the space between the first and second screens. The mold portions may then be removed so as to leave the deposited insulation adhering tothe screen I! around the winding. In order to remove all the fluid and to shrink the hydraulically applied insulation around the winding. the winding may be placed in an oven and slowly heated as is described in the abovementioned patent.

Thus, when it is desired to hydraulically build up an insulating coating having a greater thicknessthan that which may be built up for a given set of conditions under the method described in the above-mentioned patent, the insulation may be hydraulically applied according to the method described above.

In order to, insure that ing material will not stick to the screen portions 20 and II of the mold during their removal, a suitable permeable arrangement 22 may be placed separate from but contiguous with the inside surface or the screen portions 20 and 2| or the mold. This permeable envelope or bag 32 may be composed of any suitable as cloth, and may be formed if desired in two parts and having such a shape as to follow the inside contour of the screen portions 20 and 2| or the mold or be contiguous therewith. This bag member or third permeable member will then prevent any portion or the deposited insulating covering adjacent the screens 20 and 2| from sticking thereon when themold portions l and II are removed. After the insulated covered coil member has been suitably dried so as to form the covering into a homogeneous mass the bag member 32 may be left on or remo In Fig. 3 I have illustrated the insulated winding and it will be seen that two coatings are provided, one coating 35 which was produced by the passage oi the fluid -through the screen It and another coating 2' which was provided by the passage of the fluid through the mold screen. Due to the opposite movement 01 the fluids to provide these two space 31 may obtain between these two coverings. However, when the finished winding is placed in material, such the coating or insulatbetween a transformer which is suitably impregnated with an insulating or dielectric fluid such as oil the space 31 may provide a, duct which is fllled with the insulating fluid.

In Fig. 4 I have illustrated a coil winding for an electric apparatus illustrating a modified arrangement of obtaining a channel arrangement between the surrounding screen and the turns. The structure includes a plurality of turns 40, at least two adjacent turns being spaced by axially extending spacers ti and radially extending spacers l2. iwhen a suitable screen 43 formed of any suitable material permeable to the fluid is placed around the turns it will be seen that the portion of the screen which bridges between the spaced turns will produce a channel and the screen has a passage communicating with the pipe II through which the fluid may be withdrawn during the application 01' the hydraulically applied insulation upon a pressure diflerentiai being built up in any suitable manner, such as described above.

In Fig. 6 I have illustrated a modification of the method described above in which the fluid with the suspend insulating .bits only passes through the mold screens and not through any screen which surrounds the winding. Thus a winding II is provided which has no screen and when a fluid having a suitable insulating suspension is introduced through the pipe 22 into the space between the winding II and the screens II and 2|, the fluid willpass through the screens 2. and 2i and deposit its suspension. After the insulation has been built up until it this e pace the screens 2| and 2| and the-article to be coated, all surplus fluid may be withdrawn through the pipe 2i so that upon removal oi the mold portions II and II, the insulating covering will adhere to the article II. In order to insure that the insulation deposit will not adhere to the mold screens 2| and 2| the bag 22 may be employed, or a suitable gas, such as air under pressure may be introduced into the interior of the mold through the-port ll before removing it for breaking any bond or adhesions which may 'obtain between the outside surface of the deposited insulation and the inside surface of the mold v screens 2. and 2|.

After removal of the mold the insulated winding may be suitably heated so as to drive out all the fluid from the insulated covering and so as it will shrink around the winding ll.

Although I have shown and described particular embodiments of my invention, I do not desire to be limited to the particular embodiments described, and I intend in the appended claims to cover all modifications which do not depart from covering a relatively small the spirit and scope 01' my invention.

What I claim as new and desire to secure by Letters Patent 01' the United States is:

- 1. In a method oi producing an insulated electrical conducting member, the steps of surrounding the member with a permeable screen, surrounding the member and first screen with a second permeable screen and spacing the second screen from the first screen, introducing a fluid having bits of insulating material suspended therein in the space between the screens. creating a higher pressure in the liquid between the two screens than that on the other side of the screens so that the fluid will pass through the two screens and deposit its suspension thereon, and removing the second screen leaving the insulation around the first screen.

2. In a method or producin an insulated electrical conducting member, the steps of surrounding the member with a permeable screen, surrounding the member and first screen with a second permeable screen and spacing the second screen from the flrst screen, introducing a fluid having bits of insulating material suspended therein in the space between the screens, creating a higher pressure in the liquid between the two screens than that on the other side of the screens so that the fluid will pass through the two screens and deposit its suspension thereon, removing the fluid from the deposited insulation between the two screens, and removing the second screen leaving the insulation aroundthe first screen.

3. In a method of producing an insulated coil winding member for an electric induction apparatus, the steps oi surrounding the member with a screen and spacing the screen from the winding member, introducing a fluid having bits of insulating material suspended therein in the space between the member and the screen,

creating a higher pressure in the liquid between the screen and member than that outside the screen so that the fluid will pass through the screen and deposit its suspension in the space between the member and screen, removing the fluid from the deposited insulation. and removing the screen leaving the insulation around the member.

4. In a method of producing an insulated coil winding member for an electric induction appa-' ratus, the steps of surrounding the member with a permeable envelope and spacing the envelope from the member, surrounding the envelope with a screen, introducing a fluid having bits of insulating material suspended therein in the space between the member and the envelope. creating a higher pressure in the liquid between the member and envelope than that outside the screen so that the fluid will pass through thl envelope and screen and deposit its suspension in the space between the member and envelope. and removing the screen leaving the insulation and envelope around the member.

5. An insulated coil winding for an electric induction apparatus including a plurality of turns, screen means permeable to a fluid surrounding said turns, means spacing at least one of said turns from another in order to form a fluid channel between said spaced turns and said screen, and a hydraulically applied insulating material surrounding and closely fitting said screen, said screen having a fluid passage connected to said channel through which a fluid may' pass during application of said hydrau lically applied insulating material.

6. An insulated coil winding for an electric induction apparatus including a conductor turn, screen means permeable toa fluid surrounding said conductor turn, means spacing at least a portion of said screen from said turn in order to form a fluid channel between said turn and said screen, and a plurality of concentric hydraulically applied insulating coverings surrounding said screen, said coverings being spaced during application so as to provide a duct therebetween.

'I. In a method for producing an insulated electrical conducting member, the steps of surrounding the member with a permeable screen and spacing at least a portion of the screen from the member to form a fluid channel, surrounding the member and first screen with a second permeable screen and spacing the second screen from the first screen, introducing a fluid having bits of insulating material suspended therein in the space between the screens, creating a higher pressure in the liquid between the two screens than that in the channel inside the first screen and outside the second screen so that the fluid will pass through the two screens and deposit its suspension thereon, and removing the second screen leaving the insulation around the first screen.

8. In a method of producing an insulated electrical conducting member, the steps of surrounding the member with a permeable screen, surrounding the member and first screen with a second permeable screen and spacing the second screen from the flrst screen, providing a permeable bag contiguous with the inner surface of the second screen, introducing a fluid having bits oi insulating material suspended therein in the space between the screens, creating a higher pressure in the liquid between the two screens than that on the other side of the screens so that the fluid will pass through the two screens and deposit its suspension between the two screens, and removing the second screen leaving the insulation around the first screen and inside the permeable bag.

9. In a method of producing an insulated coil winding member for an electric induction apparatus, the steps of surrounding the member with a screen and spacing the screen from the member, introducing a fluid having bits of insulating material suspended therein in the space between the member and the screen, creating a higher pressure in the liquid between the screen and member than that outside the screen so that the fluid will pass through the screen and deposit its suspension in the space between the member and the screen, removing the fluid from the deposited insulation, introducing gas around the screen so as to break away any adhesions between the deposited insulation and the inside surface of the screen, and removing the screen leaving the insulation around the member.

GUGLIELMO CAMILLI.

CERTIFICATE OF CORRECTION. Patent No. 2,350,72h- June 6, 19141;. GUGLIELHQ CAHILLI- It is hereby certified that error appears in the printed specification of the above numbered patent requiring eorrectionas follows; Page 2, second column, lines 20 to 22, inclusive, strike out the words 'uponepressure differential being built up in any suita le manner, such as described. above and insert the same after the word "suspension" in line 35,-end that the said Letters Patent should be read with this correction therein that the Same may conform to the record of the casein the Patent Office.

Signed and sealed this 8th day of August, A. D. 191 1;.

Leslie Frazer (Seal) Acting Commissioner of Patents.

CERTIFICATE OF CORRECTION.

Patent No. 2,550,721. June 6, 19M;

GUGLIELMO CAMILLI It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows; Page 2, sec- 0nd column, lines Z) to 22, inclusive, strike out the words "uponapressure differential being built up in any suitable manner, such as described. above" and insert the some after the word suspension in line 353 91101 that the said Letters Patent should be read with. this correction therein that the Same may conform to the record of the 08.36 in the Patent Office.

Signed and. sealed this 8th da of August, A. D. 19141;.

Leslie Frazer (Seal) Acting Commissioner of Patents. 

